NOx Prediction Method Using EGR Ratio and Environmental Corrections
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Solution Overview
Problem
Conventional methods for predicting NOx amounts in exhaust gases are inaccurate, especially during transient engine conditions, and rely on maps or NOx sensors that have limitations in temperature and operational efficiency.
Innovation Solution
A method that corrects NOx predictions using an EGR ratio and environmental factors, involving primary corrections based on EGR deviations and secondary corrections using multiple coefficients derived from engine conditions and air supply parameters, to improve prediction accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a map-based method is used to predict NOx amount at steady state, then prediction is simple to implement, but prediction accuracy deteriorates during transient engine conditions
Solution Approach 1:
The patent transitions from a static map-based prediction method to a dynamic correction method that continuously adjusts NOx predictions based on real-time EGR ratio deviations and environmental factors. The correction coefficients are dynamically calculated based on current engine operating conditions, allowing the system to adapt to transient states while maintaining the simplicity of map-based lookup for base predictions.
Solution Approach 2:
The patent introduces correction coefficients that are determined by changing parameters such as EGR ratio deviation, intake air temperature, and coolant temperature. These parameter changes allow the system to adjust the base NOx prediction from the map to account for transient conditions, thereby improving prediction accuracy without completely replacing the simple map-based approach.
2Measurement precision
If a NOx sensor is used to detect NOx amount, then real-time detection is possible, but the sensor fails to operate below a predetermined temperature
Solution Approach 1:
The patent introduces correction coefficients as an intermediary mechanism that bridges the gap during cold start conditions. Instead of relying directly on the NOx sensor which is inactive at low temperatures, the system uses correction coefficients derived from other sensors (intake air temperature, coolant temperature) to adjust the map-based predictions, effectively mediating the detection function when the primary sensor is non-operational.
Solution Approach 2:
The system performs preliminary correction of NOx predictions using temperature-based correction coefficients before the NOx sensor becomes operational. This preliminary action ensures accurate NOx prediction during the cold start phase when the sensor cannot yet provide reliable data, allowing the exhaust control system to function correctly from engine startup.
3Adaptability or versatility
If the engine operates at transient state, then driving conditions change dynamically, but the difference between actual and predicted NOx amount increases
Solution Approach 1:
The patent implements a feedback mechanism where the actual EGR ratio is continuously monitored and compared with the map-based reference EGR ratio. The deviation between these values feeds back into the correction coefficient calculation, allowing the system to continuously refine NOx predictions during transient operations. This feedback loop enables the system to track and compensate for dynamic changes in real-time.
Solution Approach 2:
The system dynamically adjusts prediction accuracy by incorporating real-time EGR ratio deviations and environmental factor changes into correction coefficients. This dynamic approach allows the prediction system to track transient engine behavior, maintaining accuracy despite changing driving conditions by continuously adapting the correction factors based on current operational deviations.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables precise NOx prediction, enhancing purification efficiency and reducing errors, thereby improving fuel economy and reducing the need for additional sensors.
Implementation Method 1
the nitrogen oxide contained in the exhaust gas is reduced in the DE-NOx catalyst through oxidation-reduction reaction with the reducing agents
Implementation Method 2
The LNT catalyst absorbs the nitrogen oxide contained in the exhaust gas when the engine operates in a lean atmosphere, and releases the absorbed nitrogen oxide when the engine operates in a rich atmosphere
Data Source
AI summary
A method for predicting a NOx amount, may include determining a reference NOx amount according to a driving condition of an engine, primarily correcting the reference NOx amount according to an exhaust gas recirculation (EGR) ratio, and secondarily correcting the primarily corrected NOx amount according to an environmental factor and the driving condition.